Elevator safety device



7, 1956 H. SMITH ELEVATOR SAFETY DEVICE 5 Sheets-Sheet 1 Filed NOV. 14, -l95l Hewz'ZZ Smith INVENTOR I I I ATTORNEYS.

Aug. 7, 1956 H. SMITH ELEVATOR SAFETY DEVICE s Sheets-Sheet 2 I Filed Nov. 14, 1951.

Hewizz Jmiih INVENTOR ATTORNEYS H. SMITH ELEVATOR SAFETY DEVICE Aug. 7, 1956 5 Sheets-Sheet 4 Filed NOV. 14, 1951 59 zoi 2'5 J77: ZZ t INVENTOR v I A ATTORNEYS Aug. 7, 1956 H. S MITH ELEVATOR SAFETY DEVICE 5 Sheets-Sheet 5 Filed Nov. 14. 1951 ATTORNEYS United States Patent" 1 2,757,757 ELEVATOR SAFETY DEVICE Hewitt Smith, Birmingham, Ala., assignor to Woodward Iron Company, Woodward, Ala. Application November 14, 1951, Serial No. 256,176 1 Claim. (Cl. 187-13) This invention relates to a safety device for an elevator and has for its primary object to prevent the descent of an elevator car should the tension on the hoist cable of the car become relaxed.

Another object is to arrest the ascent or descent of the car should it attain a predetermined velocity.

A further object is to avoid injury or loss of life of passengers occupying the car and also to prevent property damage in event that the car descends without connection to the hoist cable.

Still another object is to retard the rapidity of the descent of the car without damaging the guide rails therefor and without the application of braking effort to the rollers upon which the car rides on the guide rails.

While the invention is not so limited, it is particularly adaptable to use in connection with mine cars of the type commonly employed in transporting Working crews to and from the interior of a mine.

The above and other objects may be attained by employing this invention which embodies among its features a car mounted to move in an elongated upwardly extending rectilinear path, a hoist mounted adjacent the upper end of the rectilinear path, a draw bar carried by the car, a hoist cable connected to the hoist and to the drawbar for raising or lowering the car along the rectilinear path, a cable drum mounted on the car to rotate about an axis which lies perpendicular to the rectilinear path, an elongated cable lying adjacent the rectilinear path and anchored adjacent opposite ends thereof, said cable being looped about the cable drum, and means connected to the cable drum and to the draw bar for arresting rotation of the cable drum when the tension of thehoist cable on the draw bar is relaxed.

Other features include a brake drum carried by the car and connected to the cable drum for rotation therewith, a friction band carried by the car and encircling the brake drum, yielding means carried by the car and connected to the draw bar for moving the draw bar against the eifort of the hoist cable, and means connected to the draw bar and to the friction band for contracting said band about the brake drum when the, draw bar moves under the influence of the yielding means.

Other features include a bar mounted on the car to move longitudinally thereof, said bar being coupled to the friction band and having yielding means for contracting said band about the bar, a latch member carried by the bar, a keeper mounted on the car and normally projected into engagement with the latch member, and centrifugal means carried by the car and engaging the cable for. rotation by said cable and means movable in a path which when the speed of rotation of the centrifugal means attains a predetermined value intersects the keeper and moves it to disengage the latch member to thereby permit the harm movelongitudinally of the carand contract the friction band about the brake drum.

In the drawings,

Fig. 1 is a side view of a trackway and car thereon of the type employed as an elevator in carrying mine crews to and from the working level of a mine, I V

1 Fig. 2 is a side View in elevation of an elevatorcar equipped with this improved safety device, I a

v Fig. 3 is a view illustrating the manner in which, the safety cable is fitted about the cable; drums,

.Fig. .4 is a plan. view ofFig, .3, 4.4; g,

2,757,757 Patented Aug. 7, 1956 Fig. 5 is an end view of the elevator car from the draw bar end thereof,

Fig. 6 is a plan view of a fragment of the skeleton frame of the car showing the draw bar mounting thereon,

Fig. 7 is a fragmentary top plan view of the car illustrated in Fig. 5, certain parts being broken away more clearly to illustrate certain details of construction,

Fig. 8 is an end view of the car taken from the end opposite Fig. 5,

Fig. 9 is an enlarged detail fragmentary view of a portion of the car showing the draw bar supporting means in section with the draw bar and friction band operating linkage'mounted on the car,

Fig. 10 is a fragmentary enlarged detail view of the end of the car opposite the draw bar showing the friction band bar and the operating spring thereof, a

' Fig. 11 is an enlarged side view of a modified form of the invention, and

Fig. 12 is a fragmentary sectional view taken substantially along the line 12-42 of Fig. 11.

Referring to the drawings in detail the car designated generally 10 is mounted on track rails 12 to move in a rectilinear path which extends upwardly as will be readily understood upon reference to Fig. 1. Mounted adjacent the draw bar of the car it) to raise and lower the car along the rectilinear path. Anchored as at 14 adjacent the upper end of the rectilinear path by means of a conventional turn buckle 16 is a safety cable 18, the opposite end of which is anchored as at 20 adjacent the lower end of the rectilinear path. Carried by the car 10 adjacent opposite ends thereof for rotation about parallel axes which extend perpendicular to the rectilinear path are cable drums 22' and 24 about which the cable 18 is looped intermediate its ends, and connected to the drums 22 and 24 are brake drums 26 and 28 respectively which rotate with the drums 22 and 24 as the car moves in its rectilinear path. Suit-- able guide sheaves 30 and 32 are carriedby the car 10 on opposite sides of thecable drum 22 in order to maintain the cable in frictional'contact with a relatively large surface of the drum;

A friction band 3,4 is anchored at one end as at 36 to' the car 10 and encircles the drum 26, and a similar friction band 38 is anchored as at 40 to the car 10 and encircles the drum 2S.

Mounted for longitudinal sliding movement in suitablebrackets 44 carried by the car 10 is an elongated bar 46 to which is fixed at 48 the end of the friction band 34 remote from its anchorage36 to the car it) and to which" is fixed as at 50 the end of the friction band 38 opposite that which is anchored to the car 10. it will thus be seen that by moving thebar'46 longitudinally within the brack ets 44, the bands 34 and 38 may be expanded and con-- tractedfabout their respective drums 22 and 24. Carried by the car 10 adjacent one end thereof is a guide bracket 52 through which the bar'46 extends, and carried by the" bar 46 in spaced relation to the bracket 52 is a stop collar 54. A compression coil spring 56 surrounds the bar between the bracket 52 and the stop collar 54 so as'toshift the bar. 46 longitudinally with relation to the car 10 in a direction to contract the friction bands 34 and 38 about their. respective brake drums 26 and 28. Y

Carried by the bed frame 58 of the car 10 adjacent the and bracket 62 andis provided with an opening GSWhich" aligns'with the slots 64 for the reception of a pin 70 which extends through the slo't's' 64 and opening 68 to 'slidably' support the draw bar in place. Carried by the draw bar and extending through an opening in the supporting bar 60 is a stem 72 carrying adjacent its end remote from the draw bar 66 a stop collar 74 and surrounding the stem 72 and bearing against the frame member and the stop collar 74 is a compression coil spring 76 which yieldingly holds the draw bar in a retracted position. The end of the draw bar remote from the stem 72 carries a clevis 78 to which the hoist cable previously referred to is coupled so that when the cable is under tension asduring the raising or lowering of the car along the rectilinear path, the spring 76 will be under compression.

Pivotally coupled to a bracket arm 80 carried by the end of the car 10 adjacent the draw bar 66 is a lever 82 which extends downwardly from the bracket 80 and has coupled thereto adjacent its lower end a link 84 which in turn is pivotally connected to an upwardly extending bracket 86 carried by the clevis 78 so that as the draw bar 66 is moved against the effort of the spring, the lever 82 will be moved about its pivotal connection with the bracket 80 in a clockwise direction when viewed in Fig. 9.

Mounted for rocking movement about a horizontal axis in spaced brackets 88 is a rock shaft 90 carrying at one end an upwardly extending lever 92 which is coupled through the medium of links 93 to the lever 82 between the brackets 80 and the links 84 and coupled to the rock shaft 90 for rocking movement therewith adjacent the side of the car 10 is an upwardly extending lever 94' which is coupled through the medium of a turn buckle 96 to the bar 46 adjacent the end thereof remote from the stop collar 54. It will thus be seen that when pull is exerted on the draw bar 66 it will be moved against the effort of the spring 72 to move the lever 82 through the medium of the link 84 and through the medium of the link 93, the rock shaft 90 will be moved about its axis in a direction to cause the arm 94 to exert pull on the turn buckle 96 and shift the rod 46 against the effort of the spring 56 to thereby cause the friction bands 34 and 38 to expand about their respective brake drums 26 and 28. Therefore so long as the draw bar 66 is coupled to hoist cable (not shown) and the hoist cable is under tension, the friction bands 34 and 38 will be held expanded to permit the car to move freely in its rectilinear path.

In the modified form of the invention illustrated in Figs. 11 and 12, an elevator car designated generally 100 is like the car previously described equipped with a pair of longitudinally spaced cable drums 102 which are mounted to rotate about spaced parallel axes which lie perpendicular to the rectilinear path in which the car moves. In employing car 100 such as herein shown the cable 18 which lies adjacent the rectilinear path is looped about the cable drums 102 and is engaged by sheaves 104 and 106 which are mounted On the car on opposite sides of one of the drums 102. A brake drum 108 is operatively connected to each cable drum 102 for rotation therewith and encircling each brake drum 108 is a friction band 110, one end of which is anchored as at 112 to the car. An elongated longitudinally extending bar 114 is mounted in suitable guide brackets 116 carried by the car 100 for longitudinal sliding movement relative to the car, and the ends of the friction bands 110 remote from those which are coupled as at 112 to the car are fixed as at 118 to the bar 114 so that as the bar moves longi tudinally of the car 100 the bands 110 will be contracted or expanded about their respective drums 108. Like the bar 46 previously described, the bar 114 at the opposite side of the car is spring pressed to cause the bands 110 to be contracted about their respective brake drums 108, and carried by the bar 114 intermediate the ends thereof is a latch member 120. A keeper 122 is mounted in suitable guides 124 carried by the car 100 adjacent the sheave 106 and is yieldingly urged under the influence of a spring. 126 into engagement with the latch member 120 to bid the bar 114 agaimt the vefiort of its spring actuating means so as to hold the friction bands expanded about their respective brake drums 108. Carried by the latch member 122 and projecting outwardly therefrom is a finger 128 by means of which the latch member 122 is moved against the effort of the spring 126 to disengage the latch member and permit the bar 114 to move under the influence of its spring urging means in a direction to contract the bands 110 about their respective drums 108..

Carried by the sheave 1M and extending transversely thercacross is a housing 130 through which a bolt 132 extends and slides along its longitudinal axis. A compression coil spring 134' encircles the bolt within the housing 130 and engages a stop collar 136 to normally hold the bolt retracted relative to the housing. A weight 140 is mounted on the bolt 132 adjacent one end thereof for adjustment longitudinally thereon and this weight serves through the centrifugal motion of the sheave 106 through its contact with the cable 118 to move the bolt longitudinally against the effort of the spring 134 as the speed of rotation of the sheave 106 increases until the end of the bolt adjacent the weight 140 moves radially through the housing 130 into a position to engage the arm 128 and cause the keeper 122 to move against the effort of the spring 126 into disengaged position relative to the latch member 120. In this way it will be seen that the speed of movement of the car 100 along the rectilinear path will govern the contraction of the friction bands 110 about their respective drums 108. The retarding effect of the drums 108 on the drums 102 will thus cause the speed of the car to be reduced until it attains a standstill. In this way should the hoist cable which is normally connected to the car 100 become inoperative, and the car start a descent down the rectilinear path, its movement will be arrested by the contraction of the friction bands 110 about their respective brake drums 108.

With either the device disclosed in Figs. 1 through 10 inclusive or the device disclosed in Figs. 11 and 12, it is obvious that should any accident occur to the hoist cable, or hoist mechanism of the elevator, the car and its occupants will be saved from injury.

While in the foregoing there has been shown and described the prefcrred embodiment of this invention it is to be understood that minor changes in the details of construction combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as claimed.

What is claimed is:

An elevator safety device comprising an inclined track, a carriage movable on said track, an elongated flexible cable at one side of said carriage, means securing the opposite ends of said cable to the upper and lower portions of said track, a pair of grooved wheels rotatably carried by one side of said carriage, said cable being trained about said wheels, a brake drum fixed relative to each wheel, a brake band about each drum, means securing one end of each band relative to said carriage, a band operating rod at one side of said carriage, means slidably mounting said rod on said carriage; means securing the opposite end of each band to said rod, a spring connected between one end of said rod and said carriage constantly urging said rod to band contracting position, a drawbar movably carried by said carriage, and a connection between the opposite end of said rod and said drawbar whereby pull on said drawbar will move said rod to band releasing position.

References Cited in the file of this patent UNITED STATES PATEN'XS 488,137 Uren Dec. 13, 1892 527,894 Smith Oct. 23, 1894 722,502 Edison Mar. 10, 1903 1,410,118 Prockter Mar. 21, 1922 1,507,931 Prockter Sept. 9, 1924 2,196,065 Everard Apr. 2, 1940 2,286,119 Sloane June 9, 1942 

